[web/views/rdf] Take the second element of XY equivalent for non final relation When given a Yams snippet of the form `<etype> <rtype>` ``xy.xeq()`` will return the XML snippet equivalent to this relation in the form of a tuple `(subject, rtype, object)` so ``item`` will always be a tuple here. In fact, the correct code appears just a few lines above (around line 88) for final relations so I guess this is a copy-paste mistake. Closes #4745929.

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change_attribute_type('CWCache', 'timestamp', 'TZDatetime')

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change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')

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change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')

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drop_attribute('CWSource', 'synchronizing')

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add_attribute('CWSource', 'in_synchronization')